Since Festool reuses serial numbers I can see the issue to some extent. However, I do not see why a simple purchase date data set cannot be made available from the dealer registration data set.
Name I enter that
Tool I enter that
Serial # I enter that
Date registered Database provides If no date, then I know the tool is not registered.
The above scheme is a bit of bother, but if I have the tool at hand, I usually can determine, my name, which tool it is and there serial number (although not always an easy matter I see).
With this approach, the owner can see if the tool is registered and if not, only has to dig up the purchase date for that tool.
This approach would not put private information at risk since only one date would be provided. Going forward, this approach would not save much effort versus user registration, but it would make confirming previous purchases much easier for some of us.